Feeding means for grid pasting machines



Oct. 1, 1935. J. E. BROWN ET AL 2,016,031

FEEDING MEANS FOR GRID PASTING MACHINES Filed May 14, 1931 5Sheets-Sheet l Max/rams: ./o//- 5. BR WN. 440/5 5. CZARK.

Arron 5x5.

Oct. 1, 1935. 5 BROWN r AL 2,016,031

FEEDING MEANS FOR GRID PASTING MACHINES Filed May 14, 1931 3Sheets-Sheet 2 Q n Wu Arraxavevs.

Oct. 1, 1935. J. E. BROWN ET AL FEEDING MEANS FOR GRID PASTING MACHINES3 Shets-Sheet 5 Filed May 14, 1951 Patented I Oct. -1, 1935 PATENTOFFICE FEEDING MEANS FOR MACHINE SOB/ID PASTING John E. Brown and AldieB. Clark, Cleveland, Ohio, assignors to Willard Storage Battery Company,Cleveland,

West Virginia Ohio, a corporation of Application May 14 1931, Serial No.537,344

13 Claims.

This invention relates to improvements in feeding means for grid pastingmachines.

One of the objects of the invention is the provision of automaticfeeding means of this character, simple in form and dependable inoperation.

Another object is the elimination of all feeding belts, and theprovision of positive means for inducing the travel of the gridsindependently of each other.

Another object is the provision of a rapidly acting pusher for quicklyconducting a griddelivered from the magazine into the grid conveyingmeans, the pusher then returning to its original position.

Another object is the provision of means for stopping the magazine feedindependently of other parts of the machine.

Still another object is the provision of means for agitating or jarringthe stack of grids in the magazine to overcpme any adherence of one gridto another caused by burrs on the trimmed edge, slightly roughenedsurfaces, or the like, and also to assist gravity in working the gridsdownwardly upon their ways and to free adjoining grids from each otherat the lower end of the magazine, where the pressure caused by theweight of the grids above is considerable.

A further object is the provision of means for automatically stoppingthe magazine feed and grid conveyor in the event that two grids oneabove the other are delivered into the conveying means.

Other objects and features of novelty will appear as we proceed with thedescription of those embodiments of the invention which, for thepurposes of the present application, we have illustrated in theaccompanying drawings, in which Figure 1 is an elevational view,partially in vertical section, of a portion of a grid pasting machineembodying the invention.

Fig. 2 is an end view of the same, showing the grid magazine in sideelevation.

Fig. 3 is a perspective view on a larger scale of a fragment of themagazine showing one of the lifting fingers.

Fig. 4 is a plan view of that portion of a grid pasting machine which isshown in Fig. 1'.

Fig. 5 is an end view of a modified form of the invention, showing themagazine in side elevation, and

Fig. 6 is a front view of the magazine shown in Fig. 5. v

' Similar reference characters refer to like parts throughout the views,

In the drawings, we have illustrated the first portion only of a gridpasting machine, the frame of which comprises posts I!) and horizontalspaced channel bars II. The path of the grids,

marked G, in their travel through the machine 5 lies principally betweenthese two channel bars.

A paste hopper A is located directly above a pasting plate I2, and isspaced therefrom just enough to permit a grid to pass between the hopperand plate, the forward end of the plate l2 being beveled off tofacilitate this entrance of the grids into the space between the hopperand plate. Within the hopper there may be mounted a bladed wheel l3which is rotated to force the paste through the interstices of thegrids, the plate l2 serving. as a backing for stopping the paste andspreading it out on the under side of the grid, as it travels over theplate.

Beyond the paste hopper the pasted grids are caused to pass betweenscrapers and wipers in 20 order to remove excess paste and to thoroughlycompact the paste retained in the grids. One such wiper is shown in Fig.4. g

The details of the grid pasting part of the machine and of the gridfeeding means immedi- 5 ately in advance of and beyond the paste hopperare not claimed herein but certain features thereof are claimed in acompanion application Serial No. 35,088 filed August '7, 1935 as acontinuation in part of the present application. 30

At the front end of the machine, to one side of the channel bars H,there is mounted a grid magazine B and associated grid deliverymechanism. In the form shown in Figs. 1 to 4 inclusive, this magazinecomprises a frame I5 having inclined upper rails l6 over which the lugsC of the grid G are adapted to run, and inclined ways I! upon which thelower edges of the grids rest and by which they are principallysupported. In the forward end of each of the rails I6 there is formed arecess which is covered by a stop plate l8 that is secured to the rail'16 by any suitable means. This recess, covered by the stop plate l8,forms a slot in which is received a lift finger I9 of a thicknessslightly less than the depth of the slot, and also slightly less thanthe thickness of one of the grids G. These fingers are preferably madeof steel, and are formed at their lower ends with eyes by means of whichthey are mounted upon pins 20 carried at the forward ends of ejectorbars 2| thatare pivotally mounted at their rear extremities upon pins 22carried by the magazine frame l5. Near the forward ends of rails H5, ata distance behind stop plates It! only slightly greater than thethickness of one grid G, there are mounted top stops 23. These stops atthe rear are flared upwardly as indicated at 24, so that as the gridsdescend along the ways, if any of them are supported out of contact withthe ways by burrs or rough surfaces on adjoining plates, the flaredsurfaces 24 will serve to wedge them down to the desired position.

The shaft through which power is furnishe to the magazine deliverymechanism is shown at 25. It carries a spur gear 26 to which drivingforce is imparted through a gear reduction unit 21 which comprises ashaft 23 upon which is mounted a gear 23 that meshes with a gear 30 onthe shaft of an electric motor 3|. Shaft 25 carries a bevel gear 32 thatmeshes with a bevel gear 33 on a shaft 34 that is mounted beneath themagazine I 5 and extends transversely across the channel bars I I,having bearings supported by said bars.

On one face of the bevel gear 33 there is a cam surface 35, againstwhich runs a cam follower 36 that is mounted upon the lower side of ayoke 31 having vertical end portions. attached to the ejector bars 2|,as indicated at 38 in Fig. 2. As the cam 35 rotates, the high spotthereof swings yoke 31 to the right, as viewed in Fig. 2, causing theejector bars 2| to swing upon their pivots 22 and thereby raise the liftfingers IS. The cam and follower 35, 36 constitute a separable driveconnection. They may be held apart by an eccentric 33 pivotally mountedon the forward end of frame l5 and engaging beneath one of the ejectorbars 2|, a handle 40 being attached to the eccentric 39 for theconvenient operation of the latter. By this means the lift fingers I!may be locked in their elevated positions in order to interrupt thedelivery of grids from the magazine, without stopping the drive andoperation of the balance of themachine.

At the forward lower end of magazine l5 there is located a stop 4| whichengages the lower edge of the foremost grid until the latter is liftedover it by the upward motion of the lift fingers l9, this motion alsoserving to elevate the grid lugs above the stop plates l3. The grid thendrops down onto a track mounted midway between the channel bars II, thetrack in this instance consisting of side ledges 42 carried by thechannel bars. An angle bar 43, mounted on one of the channel bars servesto prevent the grids from falling too far to the right, as viewed in'Fig. 2.

Beneath the channel bars opposite the magazine B there are carried twoangular brackets 44 which support a channeled casting 45 runningparallel with the bars II and halfway between them. In this castingthere is pivotally mounted the lower end of a pusher finger 46. A shortdistance therefrom there is also pivotally mounted the lower end of alever 41, the upper end of which carries a cam follower, running upon acam 48 keyed to shaft 34. The pusher finger 46 and the lever 41 arejoined by an adjustable link 49. Pusher finger 46 is urged toward tright, 85 V w in g. 1, by a spiral spring 50. Through the greater partof the rotation of shaft 34 the Pusher finger 46 is held in the positionillustrated in 1, but when the lever 41 rides into the low spot of cam48, spring 50 pulls pusher finger 46 to the right, in that figure, witha rapid motion, and the finger engaging the rear edge of a grid G on theledges 42, pushes the grid rapidly toward the right. Immediatelythereafter the cam 48 returns lever 41 to the position illustrat in Fig.1, and the pusher finger 46 is thereby re turned to its initialposition.

Referring now to the conveying means for causing the travel of grids Galong a path between the channel bars N, there are mounted at reg- 5ular intervals above and below the path of travel pairs of superposedshafts 5| and 52, the shafts 52 having fixed bearings carried by thechannel bars II, and the shafts5l having bearings in blocks 53 whichare'vertically adjustable by means 10 of screws 54 or the like, in orderto regulate the tractive engagement of the conveying means with thegrids, and in order to accommodate grids of difierent thicknesses. Eachpair of shafts 5|, 52 are geared together by means of intermeshing 15spur gears 55. Both shafts are positively driven by means of bevelgears56 carried by the shafts 52 meshing with bevel gears 51 carried byshaft 25. Each shaft 5| and 52 has mounted thereon a pair of knurledfeed wheels 56 which are spaced 20 apart transversely far enough toengage only the border portions of the grids, the wheels 58 of the uppershaft being spaced from those of the lower shaft just enough to receivethe grids between them with enough friction to produce a 25 goodtractive engagement. It will be noted by reference to Figs. 1 and 4 thatwe have located one set of knurled feed wheels directly in front of thepasting plate I 2 and another set directly behind that plate. Thelongitudinal dimension 30 of the plate I 2 is less than that of one ofthe grids, and the longitudinal distance between sets of feed wheels isless than the longitudinal dimension of a grid, so that there is alwayspositive feeding movement imparted to each grid at 35 all times, thisbeing particularly important in connection with the travel of the gridsover the pasting plate l2. Furthermore no grid is ever subjected tostrains imposed upon it by having to push along any grid or grids infront of it.

The throw of the pusher finger 46 is suificlent to advance a griddelivered from the magazine into contact with the first set of feedrolls 53. However it will be observed that the pusher finger 46 isoperated by spring pressure rather than 45 positively, so that in theevent *t; obstacle should be interposed to prevent the travel of thegrid, the pusher finger would do no damage. Furthermore, the springcontinues the application of pressure to the rear end of the grid until50 the latter is well gripped by the feed wheels 58.

In Figs. 5 and 6 we have illustrated a somewhat different form ofmagazine and grid delivery mechanism. The track upon which the gridstravel through the first part of the machine is also somewhat different,comprising a series of supporting rails 53 arranged between and parallelwith the channel bars I The feed wheels 58 are mounted on their shaftsjust outside of this track. The magazine comprises a frame 60 hav- 60ing upper rails 6| which constitute fixed ways adapted to support thelugs on the grids. At their forward .ends these rails are formed withslots of the same character as those in the rails l6 of the firstdescribed form of the invention, adapted to receive with a loose slidingfit lift fingers 62 which, like the lift fingers l9, are of a thicknessless than the thickness of one of the grids. The outer wall of each slotis formed by a plate 63 which is secured to the forward end of the rail6| by studs 64 or the like. Each of these plates carries a downwardlyand forwardly 1 clined guide arm 65, the upper rear end of whichconstitutes a stop having a function similar to that of stop plate I,previously referred to. The

function in a manner similar to the bars 2| of the first described formof the invention. They extend rearwardly beyond their pivotal mount ingshowever and have pivotal connection at their rear extremities withconnecting rods 63 that are attached to eccentric straps 69 running uponeccentrics 10 carried by the shaft 25.

At the rear of the frame 60 we mount a pair of agitator bars 1| uponpivot pins 12 which extend downwardly toward the front end of the framein a direction approximately parallel with the rails These agitator barsin their lower position clear the grids carried by the rails 6|, but intheir upper position they raise the grids slightly so as to lift thelugsthereof clear of the rails 6|. The oscillating movement of thesebars is efi'ected by means of connecting rods 13 which are pivotallyjoined at convenient points with the bars H and are attached at theirlower extremities to eccentric straps 14 which run upon eccentries 15also keyed to shaft 25. The eccentrics I6 and the eccentrics I5 are setat an angle to each other, however, so that the upward travel of thelift fingers 62 precedes by'a short interval the upward movement of theagitator bars H.

The shaft 25 also carries a cam lihaving a relatively wide face, uponwhich travels a follower wheel 11 that is mounted at the outer end of anarm 18 carried by and keyed to a shaft 19 which extends at right anglesto shaft 25 and is supported in bearings carried beneath the channelbars II. On the shaft I9, midway between the channel bars ll, there iskeyed a pusher finger 80' similar to the pusher finger 46. This fingeris urged forward by a coil spring 8| which is attached at 82 to somesuitable frame element. The circular part of cam 16 normally holdsfollower 11 in the position illustrated in' Figs. 5 and 6 against thetension of spring 8|. When the low spot of the cam approaches thefollower 11 however the latter is permitted to descend, travellingacross the face of the cam to a lower position and enabling the spring8! to swing the pusher 80 forward toadvance a delivered grid upon thetracks 59 into contact with the feed wheels 58.

In front of the forward end of the magazine we mount a lower stop 33with which the lower edge of the foremost grid is adapted to contact.when the grid is lifted by the lift fingers 62 to clear the upper stops,the lugs at the upper corners of the grid run upon the curved upper edgesurface of the guides 65, and these guides are so formed that they exerta lateral pull upon the grid lugs when the grid approaches horizontalposition, thereby pulling the lower edge of the grid up over the stop83.

At one side of the grid track there is a bracket 34 in which is mounteda rock shaft 85 carrying an arm 86 in the outer end of which is mounteda feeler 81, consisting conveniently of a wheel or roller that isadapted to run upon the upper surfaces of the grids passing over thetrack. The shaft 65 on one side of the bracket has attached thereto anarm 88 upon which there is an adjustable weight 89. At the opposite endof the shaft 65 there is an arm 90, the outer extremity of which isthreaded to receive an adjustable post 9|, having on its upper end a cap92 of insulating material. The cap 92 being urged upwardly a time frombeing raised by the lift fingers.

by weight 39 acting through lever 33 and arm 96, is caused'to close anelectric switch of any suitable form. As illustrative of such switch wehave shown herein two flexible metallic fingers 93 and 94, the cap 92pressing the finger 93 against the *5 finger 94 to close an electriccircuit through conductors 95 and 95, which are arranged to controldirectly or indirectly the flow of current to motor 3|. When the feeler8l rises a very small distance only, as whenit rides over inaccuraciesin the surface of a grid, thereby depressing cap 92 slightly, the metalfingers 93, 94 follow the cap 92 downwardly without separating. Howeverif the feeler 81 is lifted a greater distance, as when it I rides overtwo superposed grids, the cap 92 is depressed a considerable distanceand the fingers 93, 94 separate, breaking the circuit 95,96 whichcontrols the driving motor, thereby stopping the machine so that thetrouble can be corrected before any damage is done.

Operation.Before the machine is started, the magazine B is filledentirely or partially with skeleton grids, andthe paste hopper A isfilled with paste. The foremost grid in the magazine then occupies thespace directly behind stop plates i8 and in front of top stops 23, thelower edge of the grid being held back of the upper edge by the stop 4!.The motor is then started and the shaft 25 caused to turn. In the caseof the magazine construction of Fig. 2; the cam 35 then swings the yoke31 forward, rocking ejector bars 2i upwardly and causing lift fingers l9to rise until the grid lugs clear the stop plates l3 and the lower edgeof the grid clears the stop 4|. The top stops 23 prevent more than onegrid at,

The overbalanced grid then falls forward onto the track consisting ofledges 42, the side guide 43 preventing the grid from falling too farforward. The cam 48 is so positioned on the shaft 34 that it permitsforward motion of pusher finger 46 as V soon as the grid is in place onthe tracks The grid is then pushed forward by the spring actuated pusher46 into the first set of knurled feed wheels 58. These wheels beingppsitively driven immediately carry the grid forward at a predeterminedrate of speed. As the knurled wheels run upon the border portions of thegrids, no damage is done to the fragile inner structure of the latter.The movement of the grid under the influence of spring 50 is rapid, andis timed so as to space the grids apart for their further travel throughthe machine a short distance only. The pusher finger then rapidlyreturns to its initial position where it is held through the greaterpart of each revolution of the shaft 34. In the meantime also theejector bars 2! and the lift fingers l9 have returned to their positionillustrated in Fig. 2, and the stack of grids has slid down to bring theforemost one against the stops l6 and 4| and out from under the topstops 23. Should anything occur which would tend to interfere with theproper functioning of the machine, the operator may stop the delivery ofgrids to the conveying means by swinging the handle 40 to operate theeccentric latch 39, thereby holding the lift fingers l9 in their upperposition. i

The grid delivery mechanism of Figs. 5 and 6 is quite similar inoperation to that of Figs. 1 and 2, although the angle of inclination ofthe ways may be considerably less than that of Figs. 1 and 2, due to thefact that gravity is assisted by the operation of agitator bars II inworking the grids down toward the delivery end of the magazine. Thegrids in this case are supported 75 normally by their lugs resting uponthe inclined fixed rails 6|. The top stops 91 are positioned far enoughabove the rails 6| to accommodate the upper edges of the grid lugs whenthe grids are raised by the movement of bars II. This movement towardthe top stops also serves to depress any grids which are supported abovetheir proper position by frictional contact with adjacent grids. In Fig.5 the bars H are shown in their raised position, as are also the'fingers62. The high points of the two eccentrics l0 and 15 are spaced apartabout a quarter revolution, the upward movement of the bars H precedingthat of the fingers 62. The upward travel of the grids, induced by theupward swing of bars II, is not suificient to lift the grid lugs abovethe level of the upper stops, that is to say the rear ends of guide arms65. Hence there is no possibility of the second grid falling forwardover the guides 65. Furthermore, the lift fingers 62 would be in the wayof such a movement.

As previously explained, the forward edge surfaces of the guide arms 65are not merely arcs of circles struck from a point corresponding withthe lower edge of the foremost grid. On the contrary the lowerforward-ends of these guides extend forwardly far enough to'act as camsurfaces for exerting a forward pull on the grid lugs as gravity drawsthe grids downward, and by this means the lower edges of the grids arepulled over the bottom stop 83.

The grids in their travel downwardly through the magazine are supportedfirst upon the fixed rail 6! and then upon the swinging bars llalternately. Between each upward and downward motion of the bars H agrid is delivered from the magazine. When that occurs, and the fingers62 have descended, the upper edges of the grids swing forward a distanceequal to the thickness of one grid, the lower edges being restrained byfriction against the bars H which are supporting the weight of the gridsat that time. Then when the bars 'Il swing to their lower position thegrids are lowered so as to cause their weight to be supported by theirlugs from fixed rails 6|, whereupon the lower edges of the grids swingforward a distance corresponding to the thickness of one grid to bringthe foremost grid into contact with the stop 83. This forward :movementof the grids by a tilting action working first in one direction and thenin the other we have found to be most effective. It serves to loosen upthe contact between the grids at the forward end of the magazine wherethe weight of the grids above exerts considerable pressure tending tomake the grids stick together, and it serves to work apart adjacentgrids which are inclined to stick together because of burrs, surfaceroughnesses, or the like.

In the foregoing description we have necessarily gone somewhat intodetail in order to explain fully the particular embodiments of theinvention herein illustrated, but we desire it to be understood thatsuch detail disclosures are not to be construed as amounting tolimitations, except as they may be included in the appended claims.

Having thus described our invention, we claim:

1. In a machine of the class described, a grid magazine comprisinginclined ways adapted to support a series of twin grids with the lugsup, stops at the forward end of the magazine against which the foremostlugs engage, and lift fingers movable up and down directly behind saidstops and beneath the foremost lugs for the purpose of engaging theforemost lugs and raising the foremost grid to clear said stops, wherebythe grid-is delivered from the magazine.

2. In a machine of the class described, a grid magazine comprisinginclined ways adapted to 5 support a series of twin grids with the lugsup, stops at the forward end of the magazine against which the foremostlugs engage, and lift fingers of a thickness less than the thickness ofa grid. movable up and down directly behind said stops 10 and adapted toengage the lower edges of the foremost lugs for the purpose of raisingthe foremost grid to clear said stops, whereby the grid is deliveredfrom the magazine.

3. In a machine of the class described, a grid 15 magazine forsupporting a series of twin grids edgewise for movement by gravity in adownwardly inclined path, said frame comprising a pair of inclined siderails over which the lugs of the grids run, stops at the forward ends of20 said rails against which the lugs of the foremost grid engage, andlift fingers movable upwardly beneath the foremost lugs for the purposeof engaging the foremost lugs and raising the foremost grid to clearsaid stops. 25

4. In a machine of the class described, a grid magazine having inclinedways over which the grids are adapted to slide on edge, stops adapted toengage the foremost grid, lift fingers for raising the foremost grid todisengage it from said 30 stops, whereby it is adapted to drop forwardby gravity, a track upon which the delivered grid drops, a pusher forsliding the delivered grid upon said track, and associated timedoperating mechanism for raising said lift fingers and subse- 35 quentlyadvancing said pusher and lowering said lift fingers.

5. In a machine for handling storage battery grids, a magazine havingparallel inclined ways spaced apart upon which a series of twin grids 40may be supported edgewise, means for delivering grids from said ways oneby one, and means acting directly upon the grids for moving them up anddown in the magazine, whereby they are jarred into contact with saidways. 45

6. In a machine of the class described, a magazine having inclined waysupon which the lugs of twin grids are adapted to slide, an agitator barmounted in the magazine adapted to engage the lower edges of the gridsand running ap- 50 proximately parallel to said ways, stops at theforward end of the magazine, means for lifting one grid at a time oversaid stops, and means operating intermittently for actuating saidagitator bar to momentarily lift said grids out of 5 contact with theways.

7. In a machine of the class described, a megazine frame having inclinedways upon which the lugs of twin grids may slide, an agitator barpivotally mounted at the rear of said frame and 60 extending forwardlyin a direction approximately parallel to said ways, said bar in itslower po sition clearing the lower edges of grids supported upon theways, means for delivering grids one at a time from the forward end ofthe magazine, 5 and means for swinging said agitator bar upwardly toengage the bottom edges of the grids and lift the grids off said waysmomentarily.

8. In a machine of the class described, a magazine frame having inclinedways upon which the 7 lugs of twin grids may slide, an agitator barpivotaliy mounted at the rear of said frame and extending forwardly in adirection approximately parallel to said ways, said bar in its lowerposition clearing the lower edges of grids supported 7 upon the ways,stops at the forward end of the magazine for engaging the foremost grid,means operating at regular intervals for swinging the said agitator barupwardly to engage the bottom edges of the grids and lift the grids offsaid ways momentarily, the grids in the forward end of the magazinereceiving the maximum agitation, and means following closely thereafterfor lifting the foremost grid clear of said stops.

9. In a machine of the class described, a grid magazine comprising meansfor supporting a series of twin grids edgewise for movement by gravityin a downwardly'inclined'path, said means including upper and lowerelements each adapted to support the weight of the grids independentlyof the other, one of said elements comprising a fixed rail and the othercomprising a movable agitator bar approximately parallel to saidfixedrail, and means for moving said agitator bar upwardly and downwardly,whereby the grids are supported alternately upon said upper and lowerelements, and whereby as grids are removed from the forward end of themagazine one at a time gravity causes the upper and lower edges of thegrids remaining in the magazine to work downwardly alternately as thepoints of support change from lower to upper and vice versa.

10. In a machine of the class described, a grid magazine comprisinginclined ways adapted to support a series of twin grids with the lugsup, upper stops at the forward end of the magazine against which thelugs of the foremost grid engage, a lower stop at the forward end of themagazine of greater height than the upper stops and against which thelower edge of the foremost grid engages, means operating periodicallyfor lifting the forward grid suificiently to cause the grids to clearsaid upper stops, and guides extending downwardly and forwardly fromsaid upper stops over which the lugs on each grid are caused to run asthe upper edge of the grid swings downwardly due to gravity, said guidesinclining forwardly far enough to pull the lower edge of each grid oversaid bottom stop as the grid moves toward horizontal position.

11. In a machine of the class described, a magazine having inclined waysupon which the lugs of twin grids are adapted to slide, an agitator barmounted in the magazine adapted to engage the lower edges of the grids,stops at the forward end of the magazine, means for lifting one grid ata time over said stops. and means for actuating said agitator bar tomomentarily lift said grids at regular intervals out of contact with theways.

12. In a machine of the class described, a horizontal grid track, movingmeans adapted to engage the upper and lower surfaces of the grids forpositively feeding them along said track at a predetermined rate ofspeed, a grid magazine arranged adjacent said track, mechanism fordelivering grids one at a time from said magazine onto'said track to therear of said feeding means, and means operating at regularly timedintervals for pushing each delivered grid into said feeding means,whereby the grids are caused to move over the track in evenly spacedrelation.

13. In a machine of the class described, a grid magazine comprisinginclined ways adapted to support a series of twin grids with the lugsup, stops at the forward end of the magazine against which the foremostlugs engage, lift fingers movable up and down directly behind said stopsand beneath the foremost lugs for the purpose of engaging the foremostlugs and raising the foremost grid to clear said stops, and a pair ofguides inclined forwardly and downwardly from said stops over which thelugs on each grid are caused to run as the upper edge of the grid swingsdownwardly due to gravity.

JOHN E. BROWN. ALDIE B. CLARK.

